Endurance of Micro-Perforated Elements in Unmanned Ground Vechicle's Small Diesel Engine Silencer Application

As a suitable replacement for prevalent but environmentally hazardous fibrous materials used in exhaust system silencers, innovative micro-perforated (MP) elements have been progressively implemented for internal combustion engine noise control during the past decades. Although MP elements are already massproduced for IC engine noise control, surprisingly few scientific publications can still be found on the endurance of these MP elements. Recently the reliability of MP element was studied by the authors for a small four-stroke petrol engine silencer application. The results clearly demonstrated that the performance of the micro-perforated elements is influenced by the contamination of residual combustion products of the exhaust gas. In this paper the endurance of MP element tested in small industrial diesel engine application of a novel unmanned ground vehicle (UGV) has been treated. The MP element has been incorporated into specific exhaust system custom designed for the military UGV. During the test cycle the vehicle has been operated for more than 200 hours including severe off-road conditions. The acoustic performance together with the flow resistance of the silencer unit has been investigated by performing a series of comparative tests before and after the test cycle. Contamination of micro-perforated apertures by diesel soot particles in the hot exhaust gas flow as the most critical source for degradation together with metal erosion and structural deformations have been observed. This paper presents the first results on the endurance of micro perforated elements in diesel engine noise control.